If the SE's guard had to be augmented to actually fight skilled opponents, that doesn't mean they are better then Palpatine's guard. Palpatine could do the same, more to that he did have strong force sensitive guards that could actually use a wide array of force powers and lightsabers just not enough power to stroke ambition.

"There is one lesson you've yet to learn. How to become one with the Force!"
―Cin Drallig to Darth Vader